One of the most prominent means for making electrical connections embodies the concept of inserting a relatively rigid male prong into a mating and conforming female receptacle. Such is the design and arrangement of the common household electrical plug. In many industrial and transportation application, electrical connections in accord with this concept are made with pin-type connectors wherein the male prongs are generally cylindrical in shape, with the corresponding mating female receptacle sockets being in the form of hollow cylindrical shapes, e.g., tubes or tubular members, diametrically sized to accommodate insertion therein of the male pins, generally with some degree of a tight, or interference, fit, to produce acceptable levels of electrical current transmission therebetween and without sufficient localized resistance to produce unacceptable levels of heat build-up and loss of energy. Normally, both the male pin and the female socket are made of materials which are considered good electrical conductors, e.g., metals such as copper-based alloys. The contacting surfaces of these elements may be coated with a softer metallic conductor material, e.g., gold, rhodium, cadmium or nickel, to enhance the area and/or quality of surface contact therebetween and, thus, the transmission of electrical current. The male pin assemblies are normally contained in assemblies referred to herein as male couplers or, simply, couplers; the female receptacle sockets are normally contained in what are referred to herein as female socket assemblies. The assembly of a male coupler and a female socket assembly is variously referred to herein as a connector or connector assembly, with the male coupler and the female socket assembly both being connector segments.
Generally, a backshell is used to join the cable to the connector segment to which that cable is to be mounted. Conventionally, an electrical cable assembly, using one or more connector segments to join the cable to one or more other connector segments, is assembled by first sliding the backshell over the cable. If the backshell is fixed to a part of the connector segment, that part of the connector segment is also slid over the cable. Following this, the individual leads of wire of a given end of the cable are connected, e.g., by soldering, to the corresponding individual wire lead connectors of either a male pin assembly or a female receptacle socket. Frequently, the male pin assembly and the female receptacle socket, respectively, comprise cylindrical discs formed from electrically non-conductive, insulating material, e.g., bakelite, with small, spaced-apart holes formed therethrough in a direction parallel to the cylindrical axis of rotation of the discs.
For the male pin assembly, electrically conductive pins are inserted through the small, spaced-apart holes of the disc, the pins extending from both ends, of the cylindrical section of the disc, which form the faces of the disc. The pin extensions from one face of the disc serve as leads to be connected to the corresponding individual leads of wire in the given cable end, while the extensions from the opposite face of the disc serve as the actual pin sections to be inserted into corresponding individual sockets in the female receptacle socket.
Through the small, spaced-apart holes, of the disc to be used for the female receptacle socket, are inserted electrically conductive tubes or tubular members, usually to extend from only one face of the disc, with the opposite ends of the tubes being flush with the opposite face of the disc. The tube extensions from the one face of the disc serve as leads to be connected to the corresponding leads of wire in a given cable end. The corresponding pin sections, extending from the corresponding disc face of a male pin assembly, can be inserted axially into the tubes or tubular members, which are flush with the other face of the disc of the female receptacle socket, thus bringing the respective corresponding disc faces, of the male pin assembly and the female receptacle socket, into close, face-to-face proximity or abutment.
After either a male pin assembly or a female socket assembly has been connected to the wire leads of a cable end, the backshell is then slid forward along the cable into engagement with either the male coupler or the female socket assembly, as the case may be. Backshells may be assemblies which are generally similar in design, concept, structure and/or function to couplers: The couplers serve to draw the male pin assembly into engagement with a corresponding female receptacle socket, contained in a female socket assembly, to maintain the male pin assembly and the female receptacle socket together and to maintain the coupler and the female socket assembly together, and to provide a way to disengage them, respectively, without resort to the destruction of any of the components thereof; in similar fashion, the backshell assemblies may serve to draw the cable to either the male coupler or female socket assembly, and to hold and maintain the cable in position, thus preventing tension, flexure and stress in relation to the electrical connections formed between the cable wire leads and the wire leads from pins or tubular members of, respectively, the male pin assemblies and the female receptacle sockets.
The similarity between backshell assemblies and couplers depends on whether or not the intent is to enable the disconnection of the backshell assembly from its associated connector segment to enable repairs and/or modifications to be made to the male pin assemblies, the female receptacle sockets and their respective connections to the individual wire leads of the cables; if the intent is to so enable such disconnection, the backshell assemblies may be similar in design, concept, structure and/or function to couplers; if the intent is otherwise, then fundamental difference may be present. Ultimately, the cable must be mounted to a connector segment. In some cases this is done, for example, by crimping a tubular backshell, fixed to and extending from a connector segment, around the coaxial cable end, with the wire leads of that cable end extending through the tubular backshell to either the male pin assembly or the female receptacle socket; this attaches the cable end to the backshell more or less permanently. With such a design it is very difficult, if not impossible, to disassemble the tubular backshell from the cable to provide access to the wire lead connections, without damaging or destroying the backshell, the adjacent end of the cable and/or the associated connector segment and its contents. On the other hand, where a backshell assembly, similar to a coupler, is used, the tubular backshell extends from the backshell assembly, not the associated connector segment, and the backshell assembly can be separated from that connector segment to provide ready access to the wire lead connections, etc.
Where the intent is to enable disconnection of the backshell assembly from its associated connector segment, the adjoining of the backshell may be effected in generally the same manner as the adjoining of a coupler to a complementary female socket assembly, to form a connector assembly. In such a case, the purposes of the backshell assembly may be up to and including fourfold, being firstly, to provide means to mount the cable to the backshell, secondly, to provide means to mount and maintain either the male pin assembly or the female receptacle socket within a connector segment, thirdly, to provide means to disengage either the male pin assembly or the female receptacle socket from that connector segment, and fourthly, to enable access to the connections between the wire leads of the cable and either the male pin assembly or the female receptacle assembly.
In many industrial and transportation applications, electrical connectors are exposed to relatively adverse environments. Further, in particular in transportation applications, electrical connectors must meet specific requirements, e.g., light weight, compact size, strength, capability of functioning satisfactorily at extremes of temperature, wear and fatigue resistance, and general long-term reliability. Unlike the common household plug, industrial and transportation connectors are frequently exposed to long-term periods of heightened vibration, and intermittent physical shock forces. Thus means must be employed to assure that such connectors will not vibrate loose or be otherwise dislodged by shock, thus interrupting the electrical connection during operations. In addition, because the maintenance of uninterrupted electrical connection is, in may situations, quite critical in industrial application, and oft times vital in transportation applications, means must be employed to assure that such connectors are not inadvertently or accidentally disconnected, by jarring or otherwise, during maintenance or repairs.
Much of the equipment presently using electrical connectors, either internally or externally between various elements, is highly complex and sensitive, only rightfully subject to maintenance or repair by experts. Thus, ideally means must be used to insure that unauthorized maintenance or repair cannot readily be attempted. There is also a sinister aspect to consider. With the rise in terrorism, thought must be given to designing connectors and backshell assemblies which are relatively tamper-proof, i.e., which cannot be readily disconnected by hand, without special tools and/or for which the specific means of disassembly are not readily apparent to the uninitiated.
One approach to effecting a relatively tamper-proof connector design is disclosed in U.S. Pat. No. 2,784,385 wherein an electrical connector mechanism is described which cannot facilely be disconnected without multiple tools, and even then, may require two people to actually achieve disconnection; the alternative may be to damage the connector on disassembly, but even then, this would require tools. The assembly of this connector is described in U.S. Pat. No. 2,784,385 as drawing "the conductive connectors into complete and permanent contact with each other", with the system operating on a one-way ratchet, thread tightening principle, but without means to reverse the ratchet and without description of a disassembly procedure or means. But, of course, such an arrangement makes intended maintenance and repairs quite difficult where disassembly of the connector is required. U.S. Pat. No. 2,784,385 does not address or disclose means for mounting a backshell assembly to a connector segment.
Another connector device is disclosed in U.S. Pat. No. 2,890,434 wherein a two-way ratchet, thread tightening principle is used. In this design, the ratchet pawl is resilient and the ratchet teeth are designed to depress the resilient pawl upon rotation, thus permitting either assembly or disassembly of the connector by hand rotation with the application of modest torque. Such a coupler is not tamper-resistant, although it does feature ease of assembly, disassembly and reassembly as necessary for maintenance and repairs. The resistance of such a connector, however, to vibration, shock and jarring, is suspect as the pawl is not designed to be extended to near its limits of resiliency when the connector is assembled. U.S. Pat. No. 2,890,434, like U.S. Pat. No. 2,784,385, does not address or disclose means for mounting a backshell assembly to a connector segment.
U.S. Pat. No. 3,594,700 discloses an extraordinarily complicated and expensive-to-produce connector, with a modified pawl and ratchet tooth arrangement. In one embodiment the ratchet teeth are positioned circumferentially about the inner bore of a nut, with resilient pawls being formed on the outer periphery of a cup-like washer which is prevented from turning by compressive force exerted on the face of the washer by spring means. Conceptually, however, this device functions on the same principle of that disclosed in U.S. Pat. No. 2,890,434 and is subject to the same features and deficiencies. The other embodiment of U.S. Pat. No. 3,594,700 includes a ball and detent arrangement, acting as a ratchet, wherein the balls are mounted on a spring washer means and the mating detents are formed in another washer which is likewise prevented from turning by compressive force exerted on its face by spring means. This latter embodiment, like the former, incorporates a two-way ratchet principle and is likewise subject to the same features and deficiencies inherent in the design of U.S. Pat. No. 2,890,434. After explaining two extremely complex and elaborate embodiments to maintain couplers together, U.S. Pat. No. 4,359,254 discloses and teaches an overly simplistic design for joining backshell assemblies to connector segments, at column 2, lines 49-52 and lines 68-72, a design which provide virtually no means to prevent or inhibit disengagement of the backshell from a connector segment, either by intention or otherwise.
U.S. Pat. No. 3,971,614, in the third, alternate embodiment as shown in FIGS. 18-25 thereof, and in U.S. Pat. No. 4,030,798, there is likewise disclosed the use of a two-way ratchet design, with resilient pawl means. Like the device disclosed in U.S. Pat. No. 2,784,385, the ratchet teeth of U.S. Pat. Nos. 3,971,614 and 4,030,798 extend radially outwardly in respect to the cylindrical axis of the connector. However, the ratchet teeth of these two references are modified such that the teeth face angels, opposed to disassembly of the connector, are greater than the teeth face angles opposed to assembly. Thus, greater torque is required to force the resilient pawls over the teeth, upon disassembly, than is required for assembly. These two references, apparently, only differ in the specific shape of the resilient pawls. Neither of these two references disclose means for connecting backshell assemblies to connector segments. Although the design concept of the devices of these two references seems to, at least partially, overcome the problems, inherent in the designs of the previously mentioned references, of disengagement resistance to jarring, vibration and shock, this design still does not provide any means to resist tampering or otherwise unauthorized disassembly by hand and without tools.
U.S. Pat. No. 4,359,254 discloses a device which, in principle, is a mere variation of the devices taught by U.S. Pat. Nos. 3,971,614 and 4,030,798, with the difference being that U.S. Pat. No. 4,359,254 discloses a design in which both the ratchet teeth and the resilient pawls are formed integrally with the actual bodies of the threadably engageable connector segments. Otherwise, it appears that the device of U.S. Pat. No. 4,359,254 functions in a manner rather like the devices of U.S. Pat. No. 3,971,614 and 4,030,798. U.S. Pat. No. 4,359,254 neither addresses or discloses means for joining backshell assemblies to connector segments.
U.S. Pat. No. 4,703,988 conceptually combines the pawl design of U.S. Pat. No. 2,890,434 with the concept of differential ratchet teeth face angles disclosed in U.S. Pat. Nos. 3,971,614 and 4,030,798. Thus, the device of U.S. Pat. No. 4,703,988 incorporates the simplicity of design of the device of U.S. Pat. No. 2,890,434 with the apparent superior disassembly resistance of U.S. Pat. Nos. 3,971,614 and 4,030,798; nevertheless, all are two-way ratchet designs and, thus, do not incorporate means to prevent disassembly by hand and without tools. U.S. Pat. 4,703,988, like most of the foregoing, does not address or disclose means for joining backshells to connector segments.
The foregoing does not, by any means, exhaust the disclosure of various ratchet designs adapted to electrical connectors. For example, there are various designs in which the pawls themselves are not resilient, but rather are urged into engagement with differing forms of ratchet teeth by separate springs. Such designs are disclosed in U.S. Pat. Nos. 2,728,895; 3,462,727; 3,663,926; 3,808,580; 3,917,373; 4,285,564 and 4,900,260. Some of these designs include complementary ratchet teeth and pawl forms, such as U.S. Pat. Nos. 2,728,895; 3,663,929; 3,917,373; 4,285,564 and 4,900,260; while others incorporate designs where the pawls and corresponding ratchet teeth are in the form of balls and detents, respectively, such as disclosed in U.S. Pat. No. 3,462,727 and 3,808,580. Nevertheless, all of the references mentioned hereinabove in this paragraph disclose devices which can readily be disassembled by hand and without tools, thus none are particularly resistant to tampering and other unauthorized disassembly.
U.S. Pat. No. 2,728,895 discloses four (4) different embodiments of means to mount backshell assemblies to connector segments, only one of which (FIG. 6) can conceivably provide means for inhibiting disengagement thereof, although the text of U.S. Pat. No. 2,728,895 does not teach such; (see column 4, lines 60-64.) U.S. Pat. No. 3,462,727 discloses a "screw-thread 12", conceivably onto which a backshell assembly might be mounted, although such is neither taught or disclosed. U.S. Pat. No. 3,663,926, at the left side of FIG. 1, illustrates a thread which might be used to connect a backshell assembly, however such is neither taught nor disclosed. U.S. Pat. No. 3,808,580 discloses connector shells 12 and 212, with threaded outer surfaces 16 and 216, respectively; this reference, however, teaches that such are "to mount the shell on a bulkhead or other terminal structure"; (see column 2, lines 16-20 and column 3, lines 66-67.) U.S. Pat. No. 3,917,373 , in FIG. 1, left side, illustrates a thread on "plug shell 12", but there is no explanation of its purpose. Neither U.S. Pat. No. 4,285,564 nor U.S. Pat. No. 4,900,260 address or disclose means for connecting a backshell assembly to a connector segment.
The present invention seeks to overcome the deficiencies of the devices disclosed by the foregoing references, while maintaining the ability of the electrical connectors to be resistant to being uncoupled by jarring, vibration and shock, as well as resistant to tampering and other unauthorized disassembly. In addition, the present invention provides a new approach to creating an interface between either the connector segment or between a connector segment and a backshell assembly, or both, so as to provide mechanical transition between the electrical connector segments and/or the wiring harnesses to which those electrical connector segments are to be connected. This new approach permits intended field maintenance to, repair of, and/or modification to the cable assembly, the wire leads thereof and the juncture of those wire leads to the male pin assemblies and/or the female receptacle sockets, by facilitating ready disengagement of the connector segments and/or ready disengagement of the backshell assembly from the connector segments to provide access to either the male pin assembly or the female receptacle socket, or both, as well as to the connections thereof to the wire leads of the cables to which the respective connector pins or receptacle sockets are mounted. On the other hand, the indicated new approach also positively prohibits the foregoing when such is not intended. None of the above recited references seem to embody, disclose or discuss such a combination of features nor do any of them seem to disclose such in regard to either connector segments or backshell assemblies, taken as separate items.